This invention is concerned with an improved process for the preparation of 1-nitroalkene which comprises the reaction of a 1-alkene with dinitrogen tetroxide in the presence of oxygen and an ether solvent to form an alkene-dinitrogen tetroxide adduct and subsequent reaction of the resulting adduct with sodium fluoride in the presence of an inert gas.
The addition of dinitrogen tetroxide to olefins in ether solution is known to provide 1-nitro-olefins. Thus, 1-nitropropene has been prepared in the past by the reaction of propylene with dinitrogen tetroxide (N. Levy and C. W. Scaife, of the Chemical Society, Vol. 1946, pages 1093-1104). This reaction produces a mixture of compounds which include 1,2-dinitropropane, beta-nitroisopropyl nitrite and beta-nitroisopropyl nitrate. By hydrolyzing the beta-nitroisopropyl nitrite to beta-nitroisopropanol, making an ester of this alcohol, and finally, heating the ester, 1-nitro-1-propene may be obtained in about 15% to 20% yield based on the crude product. Higher yields of 1-nitro-olefin have been obtained from crude products resulting from the reaction of dinitrogen tetroxide with higher olefins, such as 1-octadecene and cyclooctene (W. K. Siefert, Journal of Organic Chemistry, Vol. 28, pages 125-129, 1963). This procedure involves treatment of the crude reaction product with an organic base, such as triethylamine, to obtain the desired nitroolefin. Ammonia has also been used in the elimination reaction, but with poorer yields.
1-Nitroalkenes are useful for the preparation of dialkylanilines as disclosed in my related copending application, Ser. No. 280,426, filed concurrently herewith. Dialkylanilines are useful intermediates for a variety of compounds having herbicidal and fungicidal activity.